Avatar and Terra Nova star Stephen Lang has joined the cast of A Good Marriage, the adaptation of a Stephen King novella.

The indie is being directed by Peter Askin and stars Joan Allen as a woman named Darcy who discovers the sinister and gruesome double life that her husband and father of their two children, played by Anthony LaPaglia, has been living. She must now decide how far she is willing to go to maintain the marriage.

Lang will play a retired investigator from the Maine Attorney General’s office who is obsessed with solving the crime.

King wrote the screenplay for the production, which is being produced by Askin, Will Battersby and Evan Pohl.The movie began shooting this week.

Lang, who is repped by Innovative Artists, just wrapped a starring turn in the ABC pilot Reckless.